In order to provide an uninterrupted power supply, operation by means of batteries, in particular rechargeable batteries, is provided besides mains operation, in case of breakdown. For being able to provide a reliable electric power supply in industrial plants, motor vehicles, and many other fields, it is necessary to monitor the state of health (SOH) of the battery, the currently available or actual battery capacity, the charge status of the battery and numerous other battery parameters. Numerous solution options are already known in this regard.
For example, DE 199 52 693 A1 describes an apparatus for the determination and display of the state of health of a battery. In particular, the charge status of a battery can be determined with the known apparatus. To this end, the apparatus is equipped with sensors for ascertaining the battery voltage, battery temperature and battery current (charging current or discharging current). The known apparatus is further equipped with an analysis circuit, which can determine the battery SOH from the measured values. The known apparatus is furthermore capable of determining a charging and/or discharging balance of the battery for determination of the energy flow as a function of the discharge depth. In this connection, the battery temperature is one of the factors considered.
In addition, a method of monitoring rechargeable batteries is described in DE 38 32 839 C2. The method serves inter alia for calculation of the capacity that can be withdrawn from a battery for various discharging currents in relationship to the associated values of the discharge characteristic. In this manner, the point when the extractable capacity for an intended discharging current falls below a permissible minimum value can be established. This method takes account of the ‘Peukert effect’, which states that, as the discharging current of a battery increases, the energy that can be withdrawn steadily decreases.
A method for determining the status of a battery is described in DE 40 07 883 A1 with which method a respective discharge voltage value measured after current extraction from the battery is compared with a voltage value which is determined from a series of charge status curves, and the voltage difference of the two values is determined. This voltage difference is compared with the stored characteristics of the particular battery type and the decrease of the maximum available battery capacity is hence determined.
A monitoring and controlling system for several batteries connected in series is described in DE 10 2007 029 156 A1, the batteries potentials thereof being tapped and evaluated in order to optimize the service life or duration of batteries in hybrid vehicles.